(a) Field of the Invention
This invention relates to novel tricyclic isoindole derivatives, to useful intermediates, to processes for their preparation and to therapeutically acceptable acid addition salts and pharmaceutical compositions of the derivatives.
More specifically, the present invention relates to novel 1,2,3,4,6,10b-hexahydropyrazino[2,1-a]isoindole and 1,3,4,10b-tetrahydropyrimido[6,1-a]isoindol-6(2H)-one derivatives possessing valuable pharmacologic properties. These derivatives are useful for treating hypertension in mammals.
(b) Description of the Prior Art
Compounds having the tricyclic isoindole nucleus are known. For example, compounds having the pyrazino[2,1-a]isoindole nucleus are disclosed by M. Winn in U.S. Pat. No. 3,597,422, issued Aug. 3, 1971. This patent discloses 1,1-dimethyl-6-phenyl-1,2,3,4-tetrahydropyrazino[2,1-a]isoindole derivatives useful as fungicides.
Compounds having the pyrimido[6,1-a]isoindole nucleus have not been reported previously. However, isomeric pyrimidoisoindoles, for example, pyrimido[2,1-a]isoindoles, have been disclosed; for example, M. Winn and H. E. Zaugg, J. Org. Chem., 34, 249 (1969). The latter reference and M. Winn and H. E. Zaugg. J. Org. Chem., 33, 3779 (1968) are cited in U.S. Pat. No. 3,597,422, noted above.